In recent years, as one way of adding value to display devices, development of display devices having flexibility (flexible displays) is in progress. Being developed as flexible displays are liquid crystal display devices, organic EL display devices, and electrophoresis display devices.
For example, Non-Patent Documents 1-3 discloses a process in which, after producing TFTs on a polyimide layer that is formed on a glass substrate, the polyimide layer is irradiated with laser light through the glass substrate, and the polyimide layer is removed from the glass substrate. According to this method, a solution of a precursor of polyimide (i.e., also referred to as polyamic acid) is applied on the glass substrate, and a polyimide layer which is obtained by imidizing this is utilized as a flexible substrate.
Moreover, Non-Patent Document 4 proposes concepts such as a high region device on polyimide (e.g., a large-sized sensor), a wallpaper display, and the like, where TFTs are fabricated on a polyimide film.    [Non-Patent Document 1] SID 07, DIGEST, 58.4, I. French et al., 1680, “Flexible Displays and Electronics Made in AM-LCD Facilities by the EPLaRTM Process”    [Non-Patent Document 2] IBM Journal of Research and Development Volume 41, numbers 1/2 1997 Optical lithography, Doany F. E., et al. “Laser release process to obtain freestanding multilayer metal-polyimide circuits”    [Non-Patent Patent Document 3] Journal of Microelectromechanical systems, Volume 7, issue 4, December 1998, pp. 416-422, Holmes, A. S., et al. “Sacrificial layer process with laser-driven release for batch assembly operations”    [Non-Patent Document 4] Applied Physics Letters, vol. 74, No. 8, Feb. 22, 1999, pp. 1177-1179, Z. Suo, et al., “Mechanics of Rollable and Foldable Film-on-Foil Electronics”